diff options
| author |   NeilBrown <neilb@suse.com> | 2017-06-05 16:49:39 +1000 |
|---|---|---|
| committer |   Shaohua Li <shli@fb.com> | 2017-06-13 10:18:01 -0700 |
| commit | cc27b0c78c79680d128dbac79de0d40556d041bb (patch) | |
| tree | 1f32d4acd29d825eecc1aef90d423cdacea8121c /drivers/md/raid1.c | |
| parent | Merge tag 'xtensa-20170612' of git://github.com/jcmvbkbc/linux-xtensa (diff) | |
| download | linux-dev-cc27b0c78c79680d128dbac79de0d40556d041bb.tar.xz linux-dev-cc27b0c78c79680d128dbac79de0d40556d041bb.zip | |
md: fix deadlock between mddev_suspend() and md_write_start()
If mddev_suspend() races with md_write_start() we can deadlock
with mddev_suspend() waiting for the request that is currently
in md_write_start() to complete the ->make_request() call,
and md_write_start() waiting for the metadata to be updated
to mark the array as 'dirty'.
As metadata updates done by md_check_recovery() only happen then
the mddev_lock() can be claimed, and as mddev_suspend() is often
called with the lock held, these threads wait indefinitely for each
other.
We fix this by having md_write_start() abort if mddev_suspend()
is happening, and ->make_request() aborts if md_write_start()
aborted.
md_make_request() can detect this abort, decrease the ->active_io
count, and wait for mddev_suspend().
Reported-by: Nix <nix@esperi.org.uk>
Fix: 68866e425be2(MD: no sync IO while suspended)
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid1.c')
| -rw-r--r-- | drivers/md/raid1.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index e1a7e3d4c5e4..c71739b87ab7 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1321,7 +1321,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, * Continue immediately if no resync is active currently. */ - md_write_start(mddev, bio); /* wait on superblock update early */ if ((bio_end_sector(bio) > mddev->suspend_lo && bio->bi_iter.bi_sector < mddev->suspend_hi) || @@ -1550,13 +1549,13 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, wake_up(&conf->wait_barrier); } -static void raid1_make_request(struct mddev *mddev, struct bio *bio) +static bool raid1_make_request(struct mddev *mddev, struct bio *bio) { sector_t sectors; if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } /* @@ -1571,8 +1570,12 @@ static void raid1_make_request(struct mddev *mddev, struct bio *bio) if (bio_data_dir(bio) == READ) raid1_read_request(mddev, bio, sectors, NULL); - else + else { + if (!md_write_start(mddev,bio)) + return false; raid1_write_request(mddev, bio, sectors); + } + return true; } static void raid1_status(struct seq_file *seq, struct mddev *mddev) |